1. Field of the Invention
The present invention relates to an endoscope system and in particular to an endoscope system capable of making observations in a front-viewing direction and also in a lateral-viewing direction simultaneously.
2. Description of the Related Art
An endoscope system which comprises an endoscope for picking up an image of an object interior of a subject to be examined, an image processing apparatus for generating an observation image of the object picked up by the endoscope and so forth has been widely used in a medical field and an industrial field.
For example, Japanese Patent Laid-Open Publication No. 2008-309860 discloses an optical system capable of simultaneously acquiring an image of an object in a front-viewing direction which corresponds to a central axis direction and an image of an object in every direction of a lateral-viewing direction, which is substantially perpendicular to the central axis direction, and an endoscope equipped with the optical system. And then, according to the endoscope equipped with the optical system as disclosed in Japanese Patent Laid-Open Publication No. 2008-309860, an image in a round shape in the front-viewing direction (a front field-of-view image) and an entire circumferential image in the lateral-viewing direction (a lateral field-of-view image) having a circular ring shape on an outer circumference of the image in the front-viewing direction (a lateral field-of-view image) are displayed on a display unit such as a monitor.